Enhancement of photocatalytic activity of Z-scheme BiO2-x/BiOI heterojunction through vacancy engineering

Abstract

Facing water pollution problems, developing a photocatalyst that can remove multiple pollutants with high redox ability is necessary. In this study, novel BiO2-x/BiOI with Z-scheme heterojunction and oxygen vacancies was synthesized by room temperature stirring process. A series of techniques including TEM, Raman, XPS and ESR confirmed BiO2-x/BiOI structure was successfully formed. Photocurrent, EIS impedance indicated the high separation efficiency of photogenerated electrons and holes between two semiconductors. The optimum sample 30% BiO2-x/BiOI can degrade 96.4% rhodamine B (RhB), 88.7% methyl orange (MO) and 74.5% tetracycline (TC) within 90 min, respectively, and can inactivate 100% E. coli and S. aureus in 15 min and 20 min, respectively. These performance was realized under lower energy consumption light source (LED light), smaller amount of catalyst and shorter reaction time compared with related BiOI-based composites. The excellent photocatalytic performance was mainly attributed to the Z-scheme BiO2-x/BiOI heterojunction with oxygen vacancy: (i) Z-scheme between BiO2-x and BiOI can induce a strong redox ability of its photo-induced electrons and holes, (ii) the oxygen vacancies in BiO2-x are conductive to the separation of photoexcited charges. This work offers a new example in improving the performance of composite semiconductor systems to be high and multiple efficiency photocatalyst.